Transistor-Like Behavior of a Bose-Einstein Condensate in a Triple Well Potential

In the last several years considerable efforts have been devoted to developing Bose-Einstein Condensate (BEC)-based devices for applications such as fundamental research, precision measurements and integrated atom optics. Such devices capable of complex functionality can be designed from simpler building blocks as is done in microelectronics. One of the most important components of microelectronics is a transistor. We demonstrate that Bose-Einstein condensate in a three well potential structure where the tunneling of atoms between two wells is controlled by the population in the third, shows behavior similar to that of an electronic field effect transistor. Namely, it exhibits switching and both absolute and differential gain. The role of quantum fluctuations is analyzed, estimates of switching time and parameters for the potential are presented.Comment: 12 pages, 12 figure

Багатовимірна структурна ідентифікація при регулярних сигналах

New structural identification algorithm at a regular signals for the multidimensional objects with unstable poles is discussed in this article. This algorithm is based on the use of transformation of Laplace for the decision of reverse control task. It allows to find the object transfer matrices from the control input and from the indignation input as a result of the quadratic functional minimization. Новий алгоритм структурної ідентифікації багатовимірних можливо нестійких об’єктів при регулярних сигналах розглянуто у статті. Зазначений алгоритм заснований на використанні перетворення Лапласу для розв’язання зворотної задачі керування. Він дозволяє знаходити матриці передатних функцій об’єкта від регульованого входу та від збурення в результаті мінімізації квадратичного функціоналу якості

Increasing the coherence time of Bose-Einstein-condensate interferometers with optical control of dynamics

Atom interferometers using Bose-Einstein condensate that is confined in a waveguide and manipulated by optical pulses have been limited by their short coherence times. We present a theoretical model that offers a physically simple explanation for the loss of contrast and propose the method for increasing the fringe contrast by recombining the atoms at a different time. A simple, quantitatively accurate, analytical expression for the optimized recombination time is presented and used to place limits on the physical parameters for which the contrast may be recovered.Comment: 34 Pages, 8 Figure

Atomic population distribution in the output ports of cold-atom interferometers with optical splitting and recombination

Cold-atom interferometers with optical splitting and recombination use off-resonant laser beams to split a cloud of Bose-Einstein condensate (BEC) into two clouds that travel along different paths and are then recombined again using optical beams. After the recombination, the BEC in general populates both the cloud at rest and the moving clouds. Measuring relative number of atoms in each of these clouds yields information about the relative phase shift accumulated by the atoms in the two moving clouds during the interferometric cycle. We derive the expression for the probability of finding any given number of atoms in each of the clouds, discuss features of the probability density distribution, analyze its dependence on the relative accumulated phase shift as a function of the strength of the interatomic interactions, and compare our results with experiment.Comment: 25 pages, 7 figure

Projections of the population size of Russia and the world

The article presents forecasts of the population of Russia and the world in General. Highlighting three variants of the forecast of a demographic situation in Russia before 2050 yr. The article presents a forecast change in population by category (male, female, able-bodied population). It is concluded that the main growth of the population to 2050 yr. will be at the expense of labour migration, primarily from CIS countries. The analysis of trends in population to 2050 yr. in different countries and continents as a whole. Presents the forecasted share of elderly population of the continents of the world in 2050 yr. conclusions about the population decline of the highly developed European countries, and the increase in the number of developing

Projections of the population size of Russia and the world

The article presents forecasts of the population of Russia and the world in General. Highlighting three variants of the forecast of a demographic situation in Russia before 2050 yr. The article presents a forecast change in population by category (male, female, able-bodied population). It is concluded that the main growth of the population to 2050 yr. will be at the expense of labour migration, primarily from CIS countries. The analysis of trends in population to 2050 yr. in different countries and continents as a whole. Presents the forecasted share of elderly population of the continents of the world in 2050 yr. conclusions about the population decline of the highly developed European countries, and the increase in the number of developing

The Dynamic Characteristics of the Manipulator With Parallel Kinematic Structure Based on Experimental Data

The chapter presents two identification techniques which the authors found most useful in examining the dynamic characteristics of a manipulator with a parallel kinematic structure as an object of control. These techniques emphasize a frequency domain approach. If all input/output signals of an object can be measured, then the first one of such techniques may be used for identification. In the case when all disturbances can’t be measured, the second identification technique may be used

Two dimensional modulational instability in photorefractive media

We study theoretically and experimentally the modulational instability of broad optical beams in photorefractive nonlinear media. We demonstrate the impact of the anisotropy of the nonlinearity on the growth rate of periodic perturbations. Our findings are confirmed by experimental measurements in a strontium barium niobate photorefractive crystal.Comment: 8 figure